Re: [ROOT] How to specify the path for the histogram in the root file?

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Jun 13 2000 - 17:26:04 MEST


Hi Zhou,
Remove the statement:
 gFile->cd(); // go back to the top directory

Rene Brun

Zhou Zhang wrote:
> 
> Hi rooters,
> 
>   I have a root file which contains some ntuples. Now I want to write a
> macro to do some analysis on these ntuples and put the results which are
> also some histograms and ntuples under a created analysis subdirectory
> which are associated with the root file. My macro is such as:
> {
>   TFile* f = new TFile("data.root");
> 
>   f->mkdir("analysis");// make a subdirectory to hold the result
> 
>   f->cd("analysis"); // change to the created subdirectory
> 
>   TH1F* p1 = TH1F("h1","h1",100, 0., 120.); //create some result histograms
>   TH1F* p2 = TH1F("h2","h2",100, 0., 1000.);
>   TH1F* p3 = TH1F("h3","h3",100, 0., 10.);
> 
>  gFile->cd(); // go back to the top directory
>  nt1->Project("h1","t0"); //fill the histogram in the subdirectory
> 
> }
> 
> It failed because h1 is not in the current directory. But I don't know how
> to specify the path for the h1. Who could tell me how to do it?
> 
>         regards,
> 
> zhou



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